feat(editor): add experimental feature citation (#11984)

Closes: [BS-3122](https://linear.app/affine-design/issue/BS-3122/footnote-definition-adapter-适配)
Closes: [BS-3123](https://linear.app/affine-design/issue/BS-3123/几个-block-card-view-适配-footnote-态)

<!-- This is an auto-generated comment: release notes by coderabbit.ai -->
## Summary by CodeRabbit

- **New Features**
  - Introduced a new citation card component and web element for displaying citations.
  - Added support for citation-style rendering in attachment, bookmark, and linked document blocks.
  - Enabled citation parsing from footnote definitions in markdown for attachments, bookmarks, and linked docs.
  - Added a feature flag to enable or disable citation features.
  - Provided new toolbar logic to disable downloads for citation-style attachments.

- **Improvements**
  - Updated block models and properties to support citation identifiers.
  - Added localization and settings for the citation experimental feature.
  - Enhanced markdown adapters to recognize and process citation footnotes.
  - Included new constants and styles for citation card display.

- **Bug Fixes**
  - Ensured readonly state is respected in block interactions and rendering for citation blocks.

- **Documentation**
  - Added exports and effects for new citation components and features.

- **Tests**
  - Updated snapshots to include citation-related properties in block data.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

packages/frontend/core/src/blocksuite/ai/components/text-renderer.ts

@@ -121,10 +121,6 @@ export class TextRenderer extends WithDisposable(ShadowlessElement) {
       font-weight: 400;
     }
 
-    .affine-paragraph-block-container {
-      line-height: 22px;
-    }
-
     .ai-answer-text-editor {
       .affine-note-block-container {
         > .affine-block-children-container {
@@ -138,6 +134,23 @@ export class TextRenderer extends WithDisposable(ShadowlessElement) {
           }
         }
       }
+
+      .affine-paragraph-block-container {
+        line-height: 22px;
+
+        .h6 {
+          padding-left: 16px;
+          color: ${unsafeCSSVarV2('text/link')};
+          font-size: var(--affine-font-base);
+
+          .toggle-icon {
+            transform: translateX(0);
+            svg {
+              color: ${unsafeCSSVarV2('text/link')};
+            }
+          }
+        }
+      }
     }
 
     .text-renderer-container {
@@ -216,6 +229,9 @@ export class TextRenderer extends WithDisposable(ShadowlessElement) {
       'affine:list',
       'affine:divider',
       'affine:latex',
+      'affine:bookmark',
+      'affine:attachment',
+      'affine:embed-linked-doc',
     ].map(flavour => ({ flavour, viewType: 'display' })),
   };
 

packages/frontend/core/src/modules/feature-flag/constant.ts

@@ -105,6 +105,16 @@ export const AFFINE_FLAGS = {
     configurable: isCanaryBuild,
     defaultState: isCanaryBuild,
   },
+  enable_citation: {
+    category: 'blocksuite',
+    bsFlag: 'enable_citation',
+    displayName:
+      'com.affine.settings.workspace.experimental-features.enable-citation.name',
+    description:
+      'com.affine.settings.workspace.experimental-features.enable-citation.description',
+    configurable: isCanaryBuild,
+    defaultState: isCanaryBuild,
+  },
 
   enable_emoji_folder_icon: {
     category: 'affine',

packages/frontend/i18n/src/i18n.gen.ts

@@ -5617,6 +5617,14 @@ export function useAFFiNEI18N(): {
       * `Let your words stand out. This also include the callout in the transcription block.`
       */
     ["com.affine.settings.workspace.experimental-features.enable-callout.description"](): string;
+    /**
+      * `Citation`
+      */
+    ["com.affine.settings.workspace.experimental-features.enable-citation.name"](): string;
+    /**
+      * `Enable citation feature.`
+      */
+    ["com.affine.settings.workspace.experimental-features.enable-citation.description"](): string;
     /**
       * `Embed Iframe Block`
       */

packages/frontend/i18n/src/resources/en.json

@@ -1402,6 +1402,8 @@
   "com.affine.settings.workspace.experimental-features.enable-block-meta.description": "Once enabled, all blocks will have created time, updated time, created by and updated by.",
   "com.affine.settings.workspace.experimental-features.enable-callout.name": "Callout",
   "com.affine.settings.workspace.experimental-features.enable-callout.description": "Let your words stand out. This also include the callout in the transcription block.",
+  "com.affine.settings.workspace.experimental-features.enable-citation.name": "Citation",
+  "com.affine.settings.workspace.experimental-features.enable-citation.description": "Enable citation feature.",
   "com.affine.settings.workspace.experimental-features.enable-embed-iframe-block.name": "Embed Iframe Block",
   "com.affine.settings.workspace.experimental-features.enable-embed-iframe-block.description": "Enables Embed Iframe Block.",
   "com.affine.settings.workspace.experimental-features.enable-emoji-folder-icon.name": "Emoji Folder Icon",